Hydraulic dynamometer



Nov. 2, 1948. E. L. CLINE 2,452,550

HYDRAULIC DYNAMOMETER Filed may 20, 1942 5 Sheets-Sheet 1 E. L. CLINE HYDRAULIC DYNAMOMETER Nov. 2, 1948.

5 Sheets-Sheet 2 Filed May 20, 1942 Nov. 2, 1948.

E. L. CLINE ummumc DYNAMOMETER 5 Sheets-Sheet 4 Filed May 20, 1942 Nov. 2, 1948. E. CLINE 2,452,550

I HYDRAULIC DYNAHOMETER Filed May 20, 1942 5 Sheets-Sheet 5 by, "'im/ atented T HYDRAULIC DYNAMOMETER Edwin H... Cline, Pasadena, Calif assignor to Clayton Manufacturing Company, Alhambra, Calif.

Application May 20, 1942, Serial No. 443,833

This invention relates to dynamometers for general use in testing motor vehicle and engine hydraulic dynamometer is the provision of a closed, uninterrupted or continuous circulating system for the liquid employed in the hydraulic brake unit. This liquid in most instances is water because of its cheapness and ready availability, .but it will be understood that any other suitable liquid may be employed. Prior known hydraulic dynamometers have employed water and other liquid mediums in a brake unit, but the arrangement was usually such that the liquid flowed continuously through the brake unit and discharged into a container open to the atmosphere, or to waste, the rate of flow being regulated manually by ordinary hand valves. The inherent defect of such arrangement is that it is impossible to maintain a constant load on the engine and to substantially duplicate the same load in repeating or making further tests on the engine. Another factor that has rendered prior hydraulic dynamometers unsatisfactory is that the liquid used therein was usually water under pressure from a city service line, the water obviously being subject to fluctuations in flow depending upon the demand, as will be readily understood, so that it was furtherimpossible to maintain a. constant dynamometer load.

In marked contrast, the present invention comprises a hydraulic brake unit having a housing or casing, a shaft rotatably mounted in the casing and a rotor wheel in the casing secured to said shaft. The casing of the brake unit is interconnected by elements of a. piping system in an endless circuit with a heat exchanger containing relatively small tubes through which the brake liquid is passed. Cooling water flows through the heat exchanger in contact with the exterior of the small tubes and effects cooling of the brake liquid before it is returned to the brake housing. The rotor of the brake unit acts, in efiect, like a centrifugal pump, causing rapid circulation of the brake liquid through the small 41 Claims. (Cl. 188-90) tubes of the heat, exchanger. The volume of brake liquid in the housing can be varied, but in normal use it contains sufiicient brake liquid to maintain a desired load on the engine being tested and, of course, the heat exchanger is completely filled with the brake liquid so that as the rotor is rotated it forces a portion of the brake liquid out of the housing and into the heat ex changer, and an equal volume is forced out of the 'heat exchanger and returned to the housing. Thus, a closed circulating system is provided for the brake liquid, and the volume of brake liquid in the housing is maintained constant for any given load and, therefore, the load imposed by the brake liquid also remains constant.

The piping system aforementioned also includes a service line and a drain line connected with the brake unit, and valves, preferably remotely controlled, are connectedin said piping so that the dynamometer operator can open one valve to admit water into the brake housing to increase the volume of liquid in the brake and thereby increase the load absorption capacity of the brake unit, or operate another valve to drain water from the brake unit to reduce the load absorption capacity of said brake unit. Once the desired loading of the brake unit has been attained, it is normally impossible for water to either get into or out of the closed system without further operation of the valves and, hence, the load absorption capacity of the brake unit will remain constant. It will be readily apparent that by varying the volume of water in the housing of the brake unit, a vehicle may be tested at any desired load corresponding to any road speed, for example, 10 to miles/hour or more.

The brake unit itself embodies a novel vane construction and is not limited to dynamometer use. On the contrary, the brake unit is useful, for example, as a vehicle brake and the housing and rotor can be readily associated with any rotating element, such as a truck propeller shaft to retard its rotation and slow down the vehicle, especially .on hills. The effectiveness of the brake can be varied by controlling the'volume of liquid in the housing by remote control means such as disclosed herein and the liquid can be cooled by circulating the same through any suitable heat exchanger. Hence, the brake unit is claimed broadly herein in combination with a heat exchanger and closed circulating system.

A very important factor contributing to the success of the present chassis dynamometer is the provision for high circulating velocity of the brake liquid through the tubes of the heat exchanger. A high circulation velocity is desirable, not merely for the purpose of adequately cooling the brake liquid, but primarily to prevent the brake unit from being subjected to variations or pulsations in load which would defeat the accuracy of the dynamometer. More explicitly, it was discovered during the development of this invention that there is a tendency for the rotor of the brake unit when rotating to force or beat air into the brake liquid, much the same as air is beaten into cream to make whipped cream. If air is thus introduced into the brake liquid and the mixture of air and liquid is circulated through a heat exchanger, there is a tendency'for the small air bubbles to collect and form relatively large pockets or slugs of air. As these air pockets reach the low pressure side of the brake housing the air actually enters the brake housing to, in effect, take the place of the air and liquid mixture that is being continuously forced out of the brake housingby the rotor into the tubes of the heat exchanger. Hence, the volume of liquid in the brake unit is momentarily slightly reduced and the load absorption capacity of the brake unit is correspondingly reduced. Immediately following the introduction of the air slug or pocket into the brake housing, a mixture of air and liquid, or liquid alone, will then be. introduced into the housing so that the volume of brake liquid in said housing is momentarily slightly increased, producing a correspondingly slight increase in the load absorption capacity of the brake unit. The intermittent or successive introductions of air and liquid into the brake housing produce objectionable fluctuations in load which prevent a constant load from being applied to the engine undergoing test.

In arriving at the present construction, it was found that the use of a suitable number of small tubes in the heat exchanger together with a high circulating velocity prevented air from collecting in slugs or pockets in the brake liquid as it was circulated through said tubes. With air pockets thus excluded from the brake liquid, the brake unit is rendered capable of maintaining any desired constant load upon the engine being tested. In addition, the high circulating velocity of the brake liquid effected by the action of the rotor and the consequent rapid cooling of said liquid in the heat exchanger keeps the brake liquid cool enough to make it feasible to use a closed system for the brake liquid.

The heat exchanger for the hydraulic brake unit is constructed so that it can be conveniently mounted in the frame of the dynamometer. This heat exchanger is preferably cooled by water under pressure drawn from a service pipe and circulated through the heat exchanger. However, any conventional cooling means such as a fan, blower, etc, (not shown) may obviously be used with the heat exchanger in lieu of water. The dynamometer frame, which carries the piping associated with the hydraulic brake unit. has suitable couplings adapted to be connected to a service line and drain line at the location where the dynamometer is set up. In the heat exchanger, the cooling water is preferably circulated in a direction opposite to the flow of the liquid to be cooled.

One of the more important objects of the invention is to provide a chassis dynamometer suitable for testing all types of motor vehicles'under conditions simulating as nearly as possible those encountered on the road.

A more specific object of the invention is to provide a dynamometer of the hydraulic type particularly adapted for use in automobile servicing establishments, breaking-in engines, in petroleum absorption capacity of the brake unit can be mainvide a closed" system in which the brake liquid tained constant, and whichcapacity can be varied by the dynamometer operator, preferably by an electrical remote control device which can be conveniently held in the hand and actuated by the operator while seated behind the steering wheel, or while standing beside the vehicle.

Still another object of the invention is to provide a hydraulic dynamometer in which the liquid employed in the brake unit, or power absorption unit, is circulated through a heat exchanger, cooled during its passage through said heat exchanger, and then returned to said unit, the unit and heat exchanger being interconnected to prois circulated.

Another object of the invention is to provide a hydraulic brake unit constructed so that a high speed rotor can be used for power or energy absorption, and whereby quick loading and unloading, together with great lugging-down ability are provided.

Still another object of the invention is to provide a hydraulic dynamometer including a brake unit and a heat exchanger arranged to provide a closed" circulating system for the brake liquid and wherein the brake liquid has a high circulation velocity to prevent the formation of air pockets or slugs in said brake liquid which would cause fluctuations in the load absorption capacity of the brake unit.

Still another object of the invention is to provide a dynamometer that can be unloaded quickly at a predetermined rate simulating acceleration conditions on the road.

A somewhat broad object of the invention is to provide a power or energy absorption device in the form of a hydraulic brake adapted for general use. That is to say, a hydraulic brake device adapted for use in a dynamometer to absorb the power delivered by an engine shaft; on a motor vehicle (for example, a heavy truck) to serve as a brake to slow down the vehicle; etc.

Still another object of the invention is to provide dynamometer apparatus that can be operated by one person who can also make any adjustments on the engine or replacements that may be necessary.

Still another object of the invention is to provide a complete chassis dynamometer apparatus which is compact, relatively simple in construction, low in cost, and which can be readily transported from one locality to another, if desired.

Further features, advantages and objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

Fig. l is a perspective view of a complete, portable chassis dynamometer apparatus including a dynamometer unit, an instrument stand, ramps and chocks;

Fig. 2 is a plan view of the chassis dynamometer unit shown in Fig. 1;

Fig. 3 is an enlarged view partially in section taken on the line 3-3 of Fig. 2, and particularly illustrating the dynamometer unit supported by its casters, with the hydraulic brake unit in elevation aseacso providing a direct reading of the horsepower be--' ing developed by the engine undergoing test;

Fig. 8 is an enlarged view through the hydraulic brake unit taken on the line 33 of Flg. 4:

1'18. 7 is a sectional view taken on the line 1-1 of Fig. 6 showing the vane arrangement in one of the sections of the brake housing;

Fig. 8 is a side elevational view of the rotor or power absorption wheel of the brake unit shown in P18. 6; 1

Fig. 9 diagrammatically illustrates the hydraulic brake unit, the load control means therefor and the heat exchanger associated therewith through which the, brake liquid is circulated and cooled;

Figs. 10 and 11 are enlarged sectional views through the heat exchanger taken on the lines Ill-ill and il--l l, respectively, of Fig. 9; and

Figs. 12 and 13 are enlarged sectional views through the heat exchanger taken on the lines l2-lt and l3-l3, respectively, of Fig. 9.

Referring now to Figs. 1 to 4 of the drawings, the portable chassis dynamometer frame is rectangular in plan and is generally identified by the numeral l. The frame 8 comprises longitudinally extending side members 2 and 3 spaced apart and interconnected by transverse end members d and E and an intermediate transverse member 6. All of the members 2 to 6 are preferably made of structural steel generally O-shaped in cross-section. The transverse members d and d are connected by a longitudinally extending section l, and the section l is connected to the side member 3 by a short transverse member ii. The frame i, as a whole, is stiffened by six gusset plates 9 positioned on the underside of the frame at each corner thereof and adjacent the transverse member 6. The parts 2 to d, inclusive, are preferablywelded together and provide a very rigid frame structure; However,--it will be understood that these parts may be riveted or otherwise secured together, if desired.

A pair of dynamometer rolls ill and ii is mounted horizontally within the frame i between the transverse members 5 and 8. The rolls i0 and H are of a length sufllcient to be engaged by both rear wheels of a motor vehicle, whereby the natural frequency of vibration of the rolls is reduced somewhat, thus avoiding resonance. The rolls are also balanced to avoid dynamic vibration during rotation. The roll It is an idler and is supported at its opposite ends in bearing blocks it, one of which is secured to the end members by bolts l3 and the other of which is secured to the intermediate transverse member 6 by bolts id. The roll it serves as a driver or power take-oil for transmitting the power from the rear wheels of a motor vehicle to the brake unit B .of the dynamometer. The roll H is mounted in bearing .blocks l5 similar to the bearim blocks l2. One of the bearing blocks i5 is secured to the end member 5 by bolts l6 and the other bearing block is secured to the intermediate transverse member 6 by bolts i1.

'18. 3 illustrates indetail themannerinwhich the rolls are. supported in the bearing blocks. All of the bearing blocks l2 and I! are similar in construction and hence a description of one will sumce for all. Each of the rolls is supported at its opposite ends in ball bearings II, the inner element ll of which is carried on a reduced extension 20 of the rolls lO-l land the outer element 2! of which is received ina rubber grommet 22 carried by the bearing blocks 12, II and serving as an insulating material. As is shown, the grommet 22. is generally U-shaped in cross-section and partially surrounds the outer ball bearing element 2|. The use of the. rubbermounted ball bearings at the opposite ends of the rolls is conducive to .very quiet operation of the rolls.

A pair of ramp members 23 is provided to enable the vehicle to bebacked onto the rolls l0 and II for test purposes. Each of the ramps 23 includes an inclined portion 24 and a substantially horizontal portion 25, the latter portion resting upon the upper edge of the side member 3 and having an extremity in close proximity to theperiphery of the roll I l. The ramps 23 are maintained in operative relation to the side member 3 by means ofremovable screws 26 which enable the ramps 23 to be readily detached when desired.

Ordinarily no dliliculty is experienced in backing a vehicle onto the rolls l0 and ii. However, in order to drive the vehicle oil? the rolls it is necessary to lock at least one roll against rotation. To accomplish this, each of the rolls l0 and l i carries a ratchet wheel 21 at the end thereof near the frame member 5 adapted to'be engaged by a manually operable pawl 28 pivotally mounted upon a pin 29 and having an integral arm 36 adapted to be grasped by the operator to eifect engagement or disengagement of the pawl.

In view of the possibility that the floor surface upon which the portable dynamometer is to be used may not be substantially level, the frame I carries three pairs of adjustable feet, one pair being secured to the-frame members 2 and 3 ad- Jacent each of the ends of the rolls iii and ii and a third pair being secured adjacent the left extremity of the frame, as best shown in Fig. 2. Each pair of feet is associated with a pair of brackets M, 32 and 33 secured to the side membars 2 and 301- the frame I by bolts 34. The feet associated with the pairs of brackets 32 and 33 are each provided with a rubber pad 38 adapted tc engage the floor and serve to prevent vibration noises. In contrast, the pair of brackets 39 carries metal feet 39 directly engaging the ground to serve as stabilizing feet for the brake end of the dynamometer.

The end frame members land 5 of the frame l I a each carry a pair of brackets 43 to receive retractable swivel casters M: The casters M are removed or retracted to enable the feet 38 and 33 to support the framed when the unit is in use. The frame I, brackets 40, casters M and feet 88 and 39 are described and illustrated in greater detail, and claimed, in a divisional application Serial No. 775,767, filed September 24, 1947.

The brake or power absorption unit of the dynamometer is generally indicated by the letter B and is probably best shown in Figs. 3, 4 and 6. This unit includes a drum-like casing or housing 50 consisting of two sections 5i and 52 having annular portions terminating in radially extending new form a seal. A brakeshaft I extends through the housing sections it and 52. The section Ii carries a bracket 51 in which is mounted a ball bearing 58 providing a support for one end of the shaft 55 and the section 52 carries a somewhat similarvbracket 5! in which is mounted a ball bearing 60 forming a support for the opposite end of said shaft. through an opening 5| (Fig. 6) in the side wall SI of the section 5! and is surrounded by packing 53 held in place by a packing gland 84. The shaft 55 also extends through an opening 65 in the side wall 66 of the casing 52 and is surrounded by packing 1 held in place by a gland 65. Thus, the shaft 56 is packed in each of the housing sections 5| and 52 so that no fluid can escape from the housing" along said shaft.

Each of the housing sections 5i and 52 is pro-v vided with integral vanes ll extending tangentially from a central hub portion ll (Figs. 6 and 7) to the inner periphery of the annular wall portion of the respective housing sections. It will be clear from Fig. '7 that nine tangential vanes iii are provided in each housing section. The vanes 10 are of uniform axial height for about twothirds of their length and hen increase in height as indicated by the inwardly inclined portions 12 (Fig. 6). In addition to the tangential vanes, each of the housing sections II and 52 carries transverse inwardly extending webs 13, one of which is disposed between each two adjacent tangential vanes III.

A dynamically balanced power absorption rotor or brake wheel 14 (Figs. 6 and 8) is disposed in the housing 5J-between the sections 5i and 52 and is secured to the shaft 58 by a key 15 received in a keyway I5 cut in said shaft. Set screws I'l extend through a hub portion 18 of the rotor II and retain said rotor in a central position on the shaft 55.

The rotor M has a central circular web I9 extending radially from the hub I8 to a pointadjacent the innermost edge of the webs I3. Upon each side of the central web 19 is disposed a series of radially extending substantially equally spaced vanes 80 which project from the hub 18 to the periphery of the rotor. The vanes 80 are of uniform axial height for about two-thirds of their length and then taper, as indicated at 8!, toward the peripheral portion of the wheel, as is best shown in Fig. 6, said vanes terminating in end portions 82 flush with the periphery of the central web 19. The tapered portions 8| are disposed at about the same distance from the axis of the shaft 55 as the inwardly inclined portions 12 of the tangential vanes I0. However, as will be observed from Fig. 6, the inclined' vane portions I2 and 8i are not parallel but diverge outwardly relative to each other to give more linear action of loading.

It will be noted from the foregoing description that the brake housing sections 5| and 52 con tain an odd number of vanes, to-wit, nine on each side wall, whereas the brake or rotor M has an even number of vanes, to-wit, eight on each side of the central web 19. For the purposes of the present invention, the relationship could be reversed. That is to say, the rotor ll could have the odd number of vanes and the casing or housing sections 5| and 52 an even number of vanes. Similarly, the tangential vanes could be formed on the rotor instead of on the housing, as will be readily apparent without further illustration or description. The object in having one of the cooperating parts provided with tangential vanes The shaft 58 extends rotor vanes cooperate to form a "working circuit for the brake liquid, as is well understood. The brake unit 5!! is mounted upon the frame I i by hearing brackets and 86 (Figs. 3 and 8),

the bearing bracket 85 being secured to the short transverse frame member 8 by bolts 81 and the bearing bracket 86 being secured to the transverse end member' I by bolts 88. The bearing brackets 85 and 86 support the brake unit 50 with the axis of the shaft 56 disposed upon an angle relative to the axis of the drive roll II. as best illustrated in Fig. 3. The disposition of the shaft 56 upon an angle makes it possible to provide a chassis dynamometer which does not require a pit, or the raising of the dynamometer frame and rolls to a substantial height above the level of the floor. I As is shown in Fig. 6, the outer end of the shaft 56 carries a ball bearing 89 which is mounted in a rubber grommet or insulator 90 in the bearing bracket 85. The opposite end of the shaft 56 is similarly mounted in a ball bearing 9! and rubber grommet 92 in the bearing bracket 85.

The brake shaft 56 (Fig. 3) carries one element 93 of a universal joint at its lowermost end and this element is connected to a cooperating element 94 carried by one end of an intermediate shaft 95. The opposite end of said intermediate shaft also carries one element 85 of a universal joint which is operatively connected to another universal joint element 91 secured to the extension 20 of the dynamometer drive roll H. Thus. it will be apparent that rotary motion imparted to the roll H by the driven wheels of a vehicle will be transmitted to the brake rotor ll through the intermediate shaft 95 and the brake shaft 55.

The housing section ii is provided with a threaded opening Hi0 (Figs. 6 and 7) adjacent the hub II or low pressure zone of the brake .unit B in which is mounted an elbow Iili connected to a section of hose I02, whereby water or other brake liquid can be returned to the housing after passing through a heat exchanger, as will be explained more fully hereinafter. The housing section 52 has a threaded opening I03 (Fig. 6) into which is threaded a pipe nipple I04 having one end of a hose I05 connected thereto. The housing. sections have registering depressions providing a pocket I!!! adjacent the opening M3 to facilitate displacement of the brake liquid by the rotor ll during unloading and for circulation through the heat exchanger referred to above. The hose section I05 serves as an inlet hose for the heat exchanger and in addition is associated with water supply, drain piping and valves for effecting loading and unloading of the brake unit B, as will also be described more fully hereinafter. The housing section 52 has a petcock I08 (Fig. 3) mounted therein at the pocket I03 to permit complete draining of the brake unit when not in use. The housing section 5| has an air check valve Hi6 mounted in. the side wall 52 thereof to permit air to enter the brake unit and prevent the formation of a vacuum therein whenever water is drained from the brake unit B. In some constructions it is also desirable to include an air bleed opening It in the housing 50 on the leeward side of one of the stator vanes iii to provide atmospheric pressure in the brake unit so that no water into said housing.

substantial pressure will be The housing section I carries a torque arm I01 (Figs. 4 and 5). One end I08 of the torque arm I01 is secured to said housing section by bolts I09 and the opposite end of said torque arm is connected to the threaded end III of a rod II2 by a self-locking nut II3. The rod H2 is part of a torque brid e device I I4 for, in effect, "weighing" the torque produced by the engine undergoing test. The rod II2 carries an arm I28 (Fig. 9) having a rounded contact finger I32 which normally engages a potentiometer coil I28. The coil I28 is arranged in a circuit, not essential to the invention claimed herein, to give a direct meter reading of the horsepower developed by the engine undergoing test, the readings being dependent upon the amount of vertical movement of the rod H2, which changes the position of the finger I32 with respect to the potentiometer coil I28 so as to vary the amount of current which will flow through said coil to a horsepower meter 35I (Fig. 1) mountedupon a stand 8. A plug I38 (Fig. 4) electrically connects the torque bridge II4 with a generator G to be briefly described later.

The torque bridge device I I4 carries a dependent boss I39 (Fig. 5) which has a stud I40 mounted therein. The stud I40 is secured to a bracket I42 on one of the gusset plates 9 by a self-locking nut I40.

The bracket 59 on the housing section 52 carries a laterally extending arm I45 (Figs. 4 and 5) constituting one element of the generator G, the inner end of which is secured to said bracket by bolts I48. The opposite end of the arm I45 ter- I41 carries a generator stator coil assembly I48 mounted upon a stem I49 which projects ithroug the portion I41 and is adjustably held in plac 245' by nuts I50 disposed uponopposite sides of said portion I41. A cooperating generator rotor I is required to introduce eign matter from gaining'entrance into the system. The pipe line I8I also includes a solenoid valve I85 interposed between the strainer I84 and the four-way fitting I52. The valve I58 serves as a "loading valve for admitting water into the brake unit housing 50 to increase the load imposed by thebrake unit and is adapted to be operated by a remote control device I51 (Figs. 1 and 9) including a push button switch I58 marked "On" which maintains the circuit closed so long as the button is held depressed by the operator. The actuation of the button switch I58 causes the solenoid valve I85 to open and thereby admit water through the hose I05 into the brake unit B to increase the volume of liquid therein and correspondingly increase the power'absorptlon capacity thereof.

As will be apparent from Fig. 9, when the button I58 is depressed, a circuit to the solenoid valve I85 is completed as follows: through lead wire I 89, push button switch I88, line I10, through the solenoid coil of the valve I85 and through the line IN to the other lead wire I12.

An outlet coupling overlying the frame member 2 is indicated at I13 (Fig. 4) and is adapted to be connected to a drain or sewer line D. The outlet coupling I13 is connected to a drain pipe line I14 which includes a solenoid valve I18 communicating with an opening of the four-way fitting I82 and serving as an unloading valve. As will be apparent, the solenoid valve I18 controls communication between the hose I05 and the drain line I14. Thus, when the valve I18 is,..energized, it will permit draining of fluid from the brake unit B through the multi-purpose hose I05 and the pipe line I14, thereby reducing the volume of liquid in the housingof the brake unit secured to the brake shaft 55 by a key I55 so that which successively pass the ends of a permanent horseshoe magnet I58. The rotor I55, in cooperation with the coil assembly I48, acts as a generator to generate voltage in proportion to the-speed of the brake shaft 55. The generator coil assembly I48 is connected in. a circuit (not shown) with the potentiometer coil I28 and to suitable meters 359 and 35I (Fig. 1) for giving a direct reading of thespeed and horsepower, respectively, that would be developed b the vehicle under test, if it were operating on the road. The manner in which the generator G is connected in circuit with the potentiometer coil I28, speed meter 350, horsepower meter 35I, etc., is fully disclosed, and claimed, in a continuation-in-part application Serial No. 775,765, filed September 24, 19437.

As has been stated hereinbefore, the hydraulic brake unit 3 is associated with a closed system including a heat exchanger for cooling the brake liquid which absorbs the power in the brake unit. Referring now to Figs. 4 and 9, the numeral I50 indicates a pipe coupling overlying the frame member 2 (Fig. 4) and adapted to be connected to a water supply line L at the location where the dynamometer is to be used. The coupling I5!) is associated with a pipe line I8I which includes a four-way fitting I52, one opening of which has a pipe nipple I53 mounted therein and to which is connected one end of the multi-purpose hose I05, previously referred to. The pipe line I5I includes and correspondingly reducing the load absorption capacity of said unit. The solenoid valve I18, like the solenoid valve I55, is adapted to be controlled from a remote point by the remote control device I51. When the operator desires to unload the brake unit, that is to say, reduce the load absorption capacity thereof, a push button switch I11 (Fig. 9) marked Oil is depressed, thereby completing the circuit to the valve I15 through the lead I59, push button switch I11, line I18, through the coil of the solenoid valve I15, through lines I19 and I" back to the lead wire I12.

It will be apparent from the foregoing that the control device I81 enables the operator to control the valve I88 or the valve I18 to respectively raise or lower the level in the brake unit B from a remote point, whereby to vary the volume of brake liquid in said brake unit to determine the load absorption capacity thereof. The control I81 is adapted to be conveniently held in the hand of the operator and can be operated, for example, when the operator is seated at the wheel of the car and is depressing the accelerator pedal with his foot.

The hose connection I05, in addition to serving as a conduit means for loading and unloading the hydraulic brake unit B, also serves as a part of the closed circulating system through which the brake liquid from the housing 50 passes from the lowest point of the system to a heat exchanger generally indicated by the numeral I80. The heat exchanger [I preferably comprises two lengths of brass pipe I 8| and I82 adapted'to be disposed parallel to each other and to be received within the hollow portion of the C-shaped side I (seven) of relatively small copper tubes I99.

11 channel member 2 of the frame I. As is shown in 2. the heat exchanger -I99-is secured to the member 2 by suitable clamping means I99.

One end ofthe pipe III is sweated into'an angle header fitting I99 and the opposite end of said pipe is sweated into a manifold or return flow fitting I94. Similarly, one end of the pipe I92 is sweated into an angle header fitting I99 and its opposite end is sweated into the reverse fiow fitting I94. Pipe I9I contains a series The tubes I99.are mounted at one end in leakproof relation "in a plug I91 having an opening for each tube, and the plug itself is mounted in the fitting I 99 in sealed relation to the inner walls of said fitting. The opposite end of the tubes I99 is received in openings I99 (Fig. 13) formed in the reverse or return flow fitting I94, the ends of the tubes being soldered or otherwise mounted in said openings so as to prevent leakage along said tubes through said openings. In a similar manner, a series (seven) of copper tubes I99 is received in the pipe I92 with one end of said tubes I99 sealingly received in openings in a plug "I (Fig. mounted in the fitting I99 and with the opposite end of said tubes received in openings I92 in the fitting I94.

It will be understood that the plugs I91 and I9I are arranged to allow fiow only through the tubes associated therewith and that the fiow from the set of tubes I99 to the set of tubes I99 is permitted by a passage I92 in. the fitting I94. It will be further understood that the flow of cooling water along the exterior of the tubes I99 and I99 through the pipes IN and I92 is in nowise restricted and that the cooling water from the pipe I9I can pass into the pipe I92 through a second passageway I94 in the fitting I94.

It will be noted from Figs. 4 and 9 that the four-way fitting I92 is connected by a pipe line I99 with an end of the angle fitting I91 and that the fitting I99 carries a pipe nipple I99 to which is connected the return hose section I92, previously referred to. Thus, the fluidin the brake housing 99 is adapted to be introduced through the hose I99 and pipe line I98 into the copper tubes I99 from whence it flows through the passage I99 into the copper-tubes I99, to be eventually returned through the hose I92 to the brake housing 59. It will be further noted that cooling water from the inlet pipe line IBI is adapted to be diverted through a pipe line 299 and introduced into the fitting I95. This water fiows through the pipe I 92 in a direction opposite to that of the brake liquid, enters the passage I94 in the fitting I84, returns through the pipe I9I (cooling the liquid contained in the tubes I99 and I99) and is then discharged through a pipe line 29I and suitable fittings into the drain pipe I14. A manually operated valve 292 is inter! posed in the line 29I to control the rate of discharge of the cooling water from the heat exchanger I99.

As is best shown in Fig. 4, the pipe line I9I terminates in a male coupling 294 and a pipe line 29! forms a continuation of the pipe line 29l and terminates in a female coupling 299. The couplings 294 and 295 are located at a height slightly above the top of the side member 2 and are adapted to be connected to hose sections 299 and 213 provided with coupling elements 29I and 214, respectively, for connection with an auxiliary radiator liquid cooling means, which it is unnecessary to describe herein in detail, mounted in the instrument stand S.

However. the auxiliary engine cooling means and the method involved are fully disclosed, and claimed, in a divisional application Serial No. 775,766, filed September 24. 1941.

The power absorption unit B and the various piping and related mechanism shown in Fig. iare enclosed by a hood 299, as is best shown in Figs. 1 to 3. The transverse bottom edges of the hood are turned inwardly as indicated at 291 (Fig. 3) and are adapted to rest upon the end frame member 4 and the intermediate transverse frame member 9. The hood 299 can be secured in place upon the frame I in any suitable manner. for example, by conventional spring hood clamps (not shown). The hood 293 is provided with an opening 299 (Fig. 3) in the zone of the coupling elements I99 and I19 and an opening 299 (Fig. 1) in the zone of the coupling elements 294 and 299, whereby to provide ready access to these couplings without requiring removal of said hood.

The instrument stand 8 comprises a cabinet 2I2 mounted upon legs 2" and 2I9 secured to cabinet side walls H9 and 2, respectively. The lower portion of each of the legs H1 and 2I9 ,includes a triangular section generally designated by the numeral 22I, the sides of the triangular portion extending beyond the base of said triangular portion and being provided with casters 222 enabling the instrument stand S to be readily moved from one location to another.

The cabinet 2I2 carries a bracket 229, Fig. i, which serves as a convenient mounting means for the electrical remote control I91, previously described, for controlling the loading and unloading valves I99 and I19, respectively. associated with the brake unit 13.

The present hydraulic brake unit B is designed to meet the testing requirements of vehicles of average weight, so as to provide the widest possible field of eilicient use for the unit in service stations, etc. However, in some instances it may be desirable to increase the capacity of the dynamometer, or to conduct certain tests requiring more accurate compensation for the exact weight of the vehicle, and this can be done by providing a flywheel and inertia weights (not shown) which will increase the inertia of 'the brake shaft 59. Dynamometers including flywheels provided with inertia weights are fully disclosed, and claimed, in a continuation-impartapplication Serial No. 775,768, filed September 24, 1947.

The portable type of dynamometer, which has been thus far described, has the advantage that it can be set up for use in a comparatively short period of time, usually not more than about thirty minutes. In order to set up the dynamometer for operation, it is usually necessary only to connect the coupling I99 to a source of water supply L and the coupling I13 to a suitable drain D, to connect the female coupling element 29I of the hose line 299 of the instrument stand to the male coupling element 294 and to connect the male coupling element 214 of the hose line 213 to the female coupling element 295. The use of the male and female couplings in the manner disclosed prevents the hose lines 299 and 213 from being improperly connected. When the described connections have been made, all of the necessary water and drain connections are complete. The only necessary electrical connections that need be made can be made through a suitable extension cord E (Fig. 4) having a plug adaptcd to be mounted in a receptacle box 493 secured to the frame member 9 by bolts 494 to bring current to the dynamometer frame. The ramps 23, of course, must be secured is t to the side member 3 of the main frame I by the screws'26 before driving a-car onto the rolls Ill and II.

Once the dynamometer apparatus has been set up, the general procedure in preparing a motor vehicle for test to determine faulty and/or malfunctioning parts of the engine and/or vehicle is to back the vehicle onto the chassis dynamometer unit so that the rear wheels are cradled between the rolls l and IL, The rear tires are inflated to the proper pressure and pawls 28 are checked to see that they are disengaged from the ratchets 21. The chocks Y are placed in front of the front wheels as a precautionary measure to prevent the vehicle from inadvertently leaving the rolls l0 and H, but with the present design normally the chocks are wholly unnecessary inasmuch as there is no tendency whatever for the wheels to ride up on the rolls during a test, regardless of the speed at which they are driven.

The valve 202 for controlling the flow of coolingwater through the heat exchanger I80 should also be opened. The vehicle engine is then started in the conventional manner, the main clutch is disengaged and the transmission is shifted into high gear. The main clutch is then engaged and the rear wheels of the vehicle will now drive the dynamometer rolls i0 and H. Driving of the roll i I will cause the rotor 14 of the brake unit B to turn at the-same speed.

The first-step in the actual testing of the engine is to open the loading valve I66 by depressing the On" button lfit'of the remote control device I61. This may be done by the operator while seated behind the steering wheel or while standing beside the vehicle. Opening of the valve I56, as previously explained herein, admits water into the brake'housing 50 through the hose I05. As the,

water flows into the housing 50 a resistance is built up to absorb the power delivered by the vehicle wheels to the dynamometer rolls l0 and l I. The vehicle can then be operated at any desired speed and, depending upon the brake resistance, at any desired throttle opening. However, in analytical work with the present dynamometer it is preferable to load the brake unit B so that it will pull down the speed of the vehicle to 20 or 25 miles per hour at wide open throttle, at which time the corresponding horsepower developed by the vehicle is noted from the horsepower meter 35| and a record made thereof on a chart. If desired, readings of vacuum and carburetor eiliciency can also be noted.

placed from the brake housing and circulated I through the closed cooling system, previously described herein. including the heat exchanger I80 containing the small tubes I86 and I90 and that a volume equal to that displaced will be continuovsly'returned to said housing by the action of the rotor ll, so that there is no tendency for the brake liquid to seriously heat up during the tests just described and, moreover, a desired constant volume of liquid is thus maintained in the brake housing assuring a desired constant load.

It will also be understood that the heat exchanger 180 and the conduit means'connectlng the same with the brake housing provide a circulating system for the brake liquid, arranged by way of example exteriorly of the working circuit, which is normally closed to the atmosphere and normally under pressures in excess of atmospheric pressure. It will be further understood that the circulating system may possibly be considered to be open to the atmosphere during unloading, i. e., at times when brake liquid is being drained from the system to reduce the torque absorption capacity of the brake unit, but that in the normal use of the brake unit the brake liquid is confined to' circulation in the closed system and cannot flow to the atmosphere or into an open tank or the equivalent.

The next step in testing the engine preferably is to subject the engine to a predetermined indexing load, or cruising load,by reducing the power absorption capacity of the dynamometer to a point equal to the load that would be required to drive the test vehicle along a practically level road at a predetermined speed. This indexing load may be taken, for convenience, as the load at which the engine is developing 17 horsepower at a vehicle speed of 40 miles per hour. The necessary loading of the brake unit B for these con ditions can be easily obtained by noting the speed and horsepower meters350 and 355i and controlling the amount of water in the brake housing through the remote control device I61. Once the desired cruising load has been placed upon the engine, the load will remain constant inasmuch as no liquid can enter or leave the closed circulating system of the brake unit without The next step in using the present dynamometer preferably is to release'the load on the brake unit B by depressing the "Off button ill of the remote control I51 to thereby actuate the unloading valve M6 to permit the water to be drained from the brake'housing 50 and thereby decrease the resistance offered by the brake unit B. The "05 button 811 is maintained depressed until the vehicle speeds up to about 40 miles per hour with wide-open throttle. whereupon the horsepower is again noted, and the vacuum readine and exhaust gases again c ecked, if desired. These two tests are usually sufficient to determine the general condition of the vehicle under severe duty, or wide-open throttle operation. It is usually under such cond tions that any misfiring of the en ine, faulty valve operation. transmission and differential noises. etc., may be noted by the operator for later correction or adjustment.

It will be understood that a portion of the liquid of the brake unit absorbing the power developed by the engine will be continuously disfurther manipulation of the control device I61 by the operator. The vehicle can then be operated at any speed from 10 to miles per hour by merely varying the throttle opening. Speeds above 60 miles per hour at level road conditions may be obtained on the dynamometer by a gradual decrease in the power absorption load of the dynamometer unit. Again, for test purposes, it will be found sufflcient to test the vehicle at cruisine speeds corresponding to those at which the vehicle was tested with wide-open throttle, namely. at 20 and 40 miles per hour, respectively. The horsepower developed at these speeds under cruisin conditions can be noted from the horsepower meter 545i and tabulated on the chart. In addition. the vacuum in the intake manifold can he recorded together with the exhaust gas analysis data. Durin the tests under cruising load. it is po s ble to further detect malfunctioning parts of th motor and drive mechanism.

The foregoing tests are those required for the vast majority of analytical work on the dvnamometer. However. the operation of the dynamometer obviously is not restricted to these speciflc tests. In some instances it is desirable to test the accelerating capacity of' the vehicle and such acceleration tests may be conveniently made after the cruising load tests. For example,

at 60 miles per hour and the brake unit B loaded by depressing the "On" button I of the remotecontrol, I" to load the brake and pull the vehicle down to a speed of 15 miles per hour at wideopen throttle.

The loadingis left at this point by releasing the "On" button I" and the throttle opening is reduced until the speed meter"! indicates a speed of 10 miles per hour. The throttle is then opened simultaneously with theactuation of the unloading or "01! button ll! of the remote control so that the brake unit B can unload. The brake unit is so designed that it will unload at a rate simulating the normal acceleration rate of a vehicle on a levelroad. This feature of the dynamometer is achieved by the restriction to the flow of the outlet liquid leaving the brake housing offered by the solenoid valve I" which has a 55-inch orifice. During the unloading, interval that it takes the brake unit 13 to unload and the acceleration capacity of the engine can be gauged from the behavior of the engine and said time interval.

The data obtained from the foregoing tests are compared with standard performance ratings for the particular vehicle tested to aid in determining when necessary adustments or replacements are to be made, and in determining what part of the vehicle should be repaired or adjusted. Thus, the prescribed dynamometer tests subject the parts of the engine and running gear to various conditions of operation corresponding to their most severe road use. Hence, if faulty parts exist, they will make themselves known to the operator during the test under which they are subjected to their severest duty. The operator's knowledge enables him to determine what parts are subjected to their severest duty during the various tests and to make such adjustments or repairs as to place the parts in maximum operating efflciency. After the analysis has been made and the difllculties corrected, final adjustments can be. made while the car is still 'on the dynamometer and in actual operation so that it can be readily determined whether or not the parts have been adjusted to develop their maximum or best performance by comparing the meter readings after adjustments have been made with readings of similar tests made before said adjustments. It is normally desired to test the engine on the fuel that will actually be used in the car and to adjust the carburetor, spark, etc., for best operation under the altitude at which average driving is to take place.

While the hydraulic brake unit B has been shown associated with a chassis dynamometer, it is to be understood that the same can be mounted upon any suitable stand (not shown) and used in making engine tests with the engine mounted upon any suitable block (not shown). Likewise, the brake unit B is not limited to dynamometer use but can be used as a vehicle brake, as generally described hereinbefore.

It will also be understood that various changes may be made in the, construction and arrangement of the parts shown herein without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. Load absorption means comprising: a hollow drum-like housing; a shaft rotatably mounted in said housing; a rotor in said housing secured in said shaft, said housing having a hub the operator can note the time portion on the interior thereof and a series of straight vanes arranged s"bstantially tangential to said hub portion and extending from said hub portion to the periphery of said housing forming a series of pockets between said vanes, said rotor having a hub portion and a plurality of radially outwardly extending vanes forming a series of pockets confronting the pockets of said housing; and means for admitting liquid into and for draining liquid from said housing.

2. Torque absorption means comprising: a housing having opposed side walls and a Perlpheral wall, each of said side walls having a central hub portion and a plurality of straight vanes extending substantially tangentially from said hub portion to said peripheral wall; a. shaft rotatably mounted in'the hub portions of said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a .web extending centrally from said hub portion to a point adjacent said peripheral wall and a series of vanes on each side of said web extending outwardly from said hub portion to the periphery of said web; and means for admitting liquid into and for exhausting liquid from said housing.

3. Torque absorption means comprising: a drum-like housing having opposed side walls and a. peripheral wall, each of said side walls having a central hub portion and a plurality of straight vanes extending substantially tangentially from said hub portion to said peripheral wall; a shaft rotatably mounted in the hub portions of said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a web extending centrally from said hub portion to a point adjacent said peripheral wall and a series of vanes on each side of said web extending radially outwardly from said hub portion but terminating short of said peripheral wall;

'and means for admitting liquid into and for exhausting liquid from said housing.

4. Means for absorbing power comprising: a drum-like housing having opposed side walls and a peripheral wall, each of said side walls having a central hub portion and a plurality of vanes extending from said hub portion to said peripheral wall, said peripheral wall having inwardly projecting transverse webs staggered circumferentially with respect to said vanes; a shaft rotatably mounted in the hub portions of said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a web extending centrally from said hub portion to a point adjacent the inner edge of said transverse webs and a series of vanes on each side of said web extending outwardly from said hub portion; and means for admitting liquid into and for exhausting liquid from said housing.

5. Means for absorbing power comprising: a drum-like housing having opposed side walls and a peripheral wall, each of said side walls having a central hub portion and a plurality of vanes extending from said hub portion to said peripheral wall and extending axially toward each other from said side walls, but terminating with their inner edges in spaced relation to each other to provide a series of pockets open at their inner sides for the full radial length of said vanes; a shaft rotatably mounted in the hub portions of said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a flat web of substantially uniform thickness extending centrally from said hub portion to a point adjacent said peripheral wall and a series of vanes on eachside of said web extend I ing outwardly from said hub portion to the outer periphery of said web but terminating short of said peripheral wall, the number of vanes on the housing being different from the number of vanes on-the rotor; whereby harmonic vibrations are prevented; and means for. admitting fluid into and for exhausting fluid from said housing.

6..Means for absorbing power comprising: a drum-like housing having opposed side walls and a peripheral wall, each of said side walls having a. central hub portion and a plurality of vanes extending substantially tangentially from said hub portion to said peripheral wall; a shaft rotatably mounted in the hub portions of .said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a flat web of substantially uniform thickness extending centrally from said hub portion to a point adjacent said peripheral wall and a series of vanes on each side of said web extending substantially radially outwardly from said hub portion to the outer periphery of said web but terminating short of said peripheral wall, the number of vanes on the housing being different from the number of vanes on the rotor, whereby harmonic vibrations are prevented; and means for admitting fluid into and for exhausting fluid from said housing.

'7. Means for absorbing power comprising: a drum-like housing having opposed side walls and a peripheral wall, each of said side walls having a central hub portion and a plurality of vanes extending substantially tangentially from said hub portion to said peripheral wall, said peripheral wall having transverse webs extending inwardly therefrom between the vanes of said side walls; a shaft rotatably mounted in the hub portions of said side walls; a rotor within said housing secured to said shaft, said rotor comprising a hub portion, a web extending centrally from said hub portion to a point adjacent the innermost edge of the transverse webs of said peripheral wall and a series of vanes on each side of said web extending substantially radially outwardly from said hub portion and terminating at the periphery of said central web, the number of vanes on said side walls being difierent from the number of vanes on the rotor, whereby harmonic vibrations are prevented; and means for admitting liquid into and for exhausting liquid from said housing.

8. Means for absorbing power comprising: a drum-like housing having opposed side walls, and a peripheral wall of substantially uniform thickness, each of said side walls having a central hub portion and a plurality of vanes extending outwardly from said hub portion to said peripheral wall and extending axially toward each other with the edges of said vanes confronting each other in spaced apart relation throughout their length; a shaft rotatably mounted in the hub portions of said side walls; a rotor within said housing secured to said shaft. said rotor com-' prising a hub portion, a web extending centrally from said hub portion between said vanes to a point adjacent said peripheral wall and a series of vanes on each side of said web extending outwardly from said hub portion to the outer periphery of said web but terminating short of said peripheral wall, the outermost portions oi said housing vanes being of increased axial depth and being a maximum at said peripheral wall, and the outermost portions of said rotor vanes being of reduced axial depth; and means for admitting fluid into'and for exhausting fluid from said housing.

"9. Means for absorbing power comprising: a drum-like housing having opposed side walls and a peripheral wall, each of said side walls having acentral hub portionand a plurality of vanes extending from said hub portion to said peripheral wall, said peripheral wall-having transverse webs extending inwardly therefrom between the vanes of said side walls: a shaft rotatably mounted in the hub portions of said side walls; :a rotor within said housing secured to said shaft, said rotor comprisinga hub portion, a web extending centrally from said hub portion to a point adjacent the innermost edge of the transverse webs of said peripheral wall and a series ofvanes on eachside of said web extending outwardly from said hub portion and terminating at the periphery of said central web, the number of vanes on said side walls being different from the number of vanes on the rotor, whereby harmonic vibrations are prevented; and means for admitting liquid into and for exhausting liquid from said housing.

10. A power absorption device comprising: a closed housing havingopposed circular side walls and a substantially cylindrical peripheral wall spacing said side walls apart, each of said side walls having a central hub portion and a plurality of vanes extending outwardly from said hub portion to said peripheral wall and extending axially toward each other, but with their inner edges terminating in spaced relation to each other and providing a series of pockets on each side wall open at the inner sides thereof for the full radial length of said vanes, a power absorption shaft rotatably mounted in the hub portions of said side walls; a rotor secured to said shaft in said housing, said rotor including a hub portion. a central radial web of uniform thickness and radially extending vanes on the opposite sides of said web providing a plurality of pockets on each side of said web confronting said peripheral wall and the pockets in said side walls, the total number of pockets in said side walls being different from the total number of pockets in said rotor; check valve means for venting said housing to the atmosphere; and means for admitting liquid into and for exhausting liquid from said housing.

11. A liquid brake device comprising: a housing including two sections, each of said sections comprising a central hub portion, a radially extending side wall and an axially extending peripheral wall, the peripheral walls of said sections projecting toward each other and being secured together in fluid-tight relation, each of said sections being provided with a series of internal vanes extending tangentially from their respective hub portions toward their respective peripheral walls and also having a series of internal webs carried by their peripheral walls with oneweb disposed between each two adjacent tangential vanes; a shaft mounted in the hubs of said housing sections; a rotor secured to said shaft between said housing sections, said rotor having a hub portion and a plurality of series of vanes extending radially outwardly from said hub portion; and means for admitting liquid into and for draining liquid from said housing.

12. Fluid brake means comprising: a housing having a substantially cylindrical peripheral wall and opposed side walls, each of saidside walls having a hub portion formed interiorly of the housing and having a series of vanes extending substantially tangentially from said hub portion to said peripheral walland providing confronting pockets .open for the entire length of said vanes, the outer portions of said tangential vanes being inclined along the inner edges thereof and extending toward but terminating in spaced relation to'each other; a shaft rotatably mounted in the hub portions of said side walls; a rotor secured to said shaft within said housing, said rotor having a hubportion and a iiat central web of substantially uniform thickness extending outwardly from said hub portion to a point in close proximity to the inner surface of the peripheral wall of said housing, said rotor also having a plurality of vanes on the opposite sides of said central web, said vanes extending radially outwardly from said hub to the outer peripheral portion of said web, the outermost portions of the vanes of said rotor being of reduced axial width and including a portion beveled outwardly and inwardly toward said web and being disposed in a zone opposite to the inclined portions of the tangential vanes of said housing; and means for admitting liquid into and for draining liquid from said housing.

13. A dynamometer comprising: a hydraulic brake unit for absorbing the power developed by an'engine being tested, said brake unit including a housing adapted to contain water for use as a brake liquid, a brake shaft *rotatably mounted in said housing, and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet and an outlet; conduit means connecting said inlet and outlet with said housing and establishing an uninterrupted flow path between the interior of said housing and said heat exchanger normally under superatmospheric pressure, said heat exchanger containing a plurality of tubes arranged so that the brake liquid in traversing said heat exchanger must flow through said tubes, said rotor serving to cause forced circulation of the brake llquidthrough said heat exchanger and conduit means in a manner to return liquid from said heat exchanger to said housing at the same rate at which said rotor forces liquid out of said housing and into said heat exchanger; a supply pipe for supplying water to said housing to increase the load absorption capacity of said brake unit, said supply pipe having a valve connected therein; and a drain pipe for discharging water to waste from said housing to decrease the load absorption capacity of said brake unit, said drain pipe being connected with said supply pipe at a point between said housing and said valve, said drain pipe having a valve connected therein adjacent its point of connection with said supply pipe.

14. A dynamometer comprising: a hydraulic brake unit for absorbing the power developed by an engine being tested, said brake unit including a housing adapted to contain water for use as a brake liquid, a brake shaft rotatably mounted in said housing, and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet and an outlet; conduit 'means respectively connecting said inlet and outlet with said housing to form an endless circuit for said brake liquid normally closed to the atmosphere, said heat exchanger containing a plurality of tubes arranged so that the brake liquid in traversing said heat exchanger must flow through said tubes, said rotor serving to cause forced circulation of the brake liquid from said housing at a given flow rate and into and through said heat exchanger and back to, said housing at the same flow rate; a supply pipe for supplying water to said housing to increase the load absorption capacity of said brake unit. said su ply pipe having an electromagnetic loading valve connected therein: a drain pipe for discharging water to waste from said housing to decrease the load absorption capacity of said brake unit, said drain pipe being connected with said supply pipe at a point between said housing and said valve, said drain pipe having an electromagnetic unloading valve connected therein adjacent its point ofconnectlon with said supply pipe; and remote control means for controlling the operation of said valves.

15. A dynamometer comprising: a hydraulic brake unit for absorbing the power developed by an engine being tested, said brake unit including a housing adapted to contain water for use as a brake liquid, a brake shaft rotatably mounted in said housing, and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet and an outlet; conduit means connecting said inlet and outlet with said housing and forming a circulating system for the brake liquid normally-under superatmospheric pressure, said heat exchanger containing a plurality of tubes arranged so that the brake liquid in traversing said heat exchanger must flow through said tubes, said rotor serving to cause forced circulation of the brake liquid through said heat exchanger; 9. supply pipe for supplying water to said housing to increase the load absorption capacity of said brake unit, said supply pipe having a loading valve connected therein; a drain pipe for discharging water to waste from said housing to decrease the load absorption capacity of said brake unit, said drain pipe being connected with said supply pipe at a point between said housing and said valve, said drain pipe having an unloading valve connected therein adjacent its point of connection with said supply pipe; means for admitting cooling water to said heat exchanger for contact with the exterior of said tubes including a conduit connecting said heat exchanger with said supply pipe at a point ahead of said loading valve; and means for discharging cooling water from said heat exchanger including a conduit connected to said drain pipe at a point on the discharge side of said unloading valve.

16. A device for absorbing the power of a driven member, comprising: a hydraulic brake unit including a housing adapted to contain any given volume of brake liquid within its capacity, and a rotor in said housing adapted to be connected with said driven member, said housing and rotor having vanes cooperable to form a working circuit for said brake liquid;'means for varying the volume of brake liquid in said working circuit at will to vary the load absorption capacity of said brake unit; a heat exchanger having an inlet and an outlet and normally being full of brake liquid; means having a passage establishing communication between the working circuit of said hydraulic brake unit and the inlet and outlet,

respectively, of said heat exchanger, said last-' mentioned means also normally being full of brake liquid, whereby to provide a closed circulatng and cooling system for the brake liquid normally closed to the atmosphere in which any given volume of brake liquid displaced from said working circuit by said rotor and forced by said rotor into said heat exchanger is simultaneously replaced by an equal volume of brake liquid formed out of said heat exchanger by the action of said rotor and returned to said working circuit, so that a constant volume of brake liquid is maintained in said work ng circut for any given load regardless of the speed of the rotor.

17. A device for absorbing the power of a driven member, comprising: a hydraulic brake unit inassasso 21 eluding a stator adapted to contain any given volume of brake liquid within its capacity, and a rotor in said stator adapted to be connected with said driven member, said stator and rotor havin means cooperable to form a working circuit for said brake liquid; a heat exchanger having inlet and outlet means in open communication with the working circuit in the interior of said stator and normally being filled with brake liquid, said rotor being adapted, as it is rotated, to positively displace brake liquid from said working circuit, force the displaced brake liquid into and through said heat exchanger, and back into said working circuit, whereby to provide a closed circulating and cooling system for the brake liquid normally operating under superatmospheric pressure and in which any given volume of brake liquid dis- I continuously force brake liquid out or said workplaced from said working circuit by said rotor and forced into said heat exchanger is simultaneously replaced by an equal volume of brake liquid forced out of said heat exchanger and returned to said working circuit, so that a constant volume of brake liquid is maintained in said stator for any given load regardless of the speed of the rotor.

18. A device for absorbing the energy of a driven member, comprising: a hydraulic brake unit including a stator adapted to contain brake liquid, and a rotor in said stator adapted to be connected with said driven member, said stator and rotor having means forming a working circuit for said brake liquid; a heat exchanger for cooling said brake liquid, said heat exchanger having inlet and outlet means for said brake liquid; and passage means having a substantially uniform cross-sectional area interconnecting said working circuit and said inlet and outlet means of said heat exchanger and cooperable therewith to provide an interrupted circulating system for said brake liquid normally closed to the atmosphere, said rotor serving to chest iorced circulation of said brake liquid by continuously forcing a given volume of said brake liquid from said working circuit, into said heat exchanger and continuously forcing an equal volume oi said brake liquid out of said heat exchanger and back into said working circuit, whereby the volume of brake liquid in said working circuit is maintained constant.

19. A device for absorbing the energy of a driven member, comprising: a hydraulic brake unit including a stator adapted to contain a brake liquid, and a rotor in said stator adapted to be connected with said driven member, said stator and rotor having means providing a working circuit for said brake liquid; and means including a heat exchanger communicating with said working circuit at diflerent points and providing a continuous, uninterrupted flow path for brake liquid exteriorly of said working circuit, said flow path being completely filled with brake liquid under hydraulic pressure normally above atmospheric pressure when said brake unit is in operation, said rotor serving as an impeller when rotating to continuously force brake liquid out of said working circuit into and through said flow path including said heat exchanger, and back into said working circuit, whereby the volume of brake liquid in said working circuit is maintained constant regardless of the speed of said rotor.

20. A device for absorbing the energy or a driven member, comprising: a hydraulic brake unit including a stator adapted to contain a brake liquid, and a rotor in said stator adapted to be connected with said driven member, said'stator ing circuit into and through said flow path including said heat exchanger, and back into said working circuit, whereby the volume of brake liquid in said working circuit is maintained constant regardless of the speed oi said rotor:- and means operable at will to vary the volume of brake liquid in said working circuit to change the load absorption capacity or said'brake unit as desired.

21. A device for absorbing the energy of a driven member, comprising: a hydraulic brake unit including a stator adapted to contain brake liquid, and a rotor in said stator adapted to be connected with said driven member, said stator having an inlet opening and an outlet opening' for brake liquid, and said stator and rotor having means forming a working circuit for said brake liquid; a heat exchanger for cooling said brake liquid, said heat exchanger having an inlet and an outlet for said brake liquid; a conduit connected at one end to said outlet opening of said stator and connected at its opposite end with said inlet or said heat exchanger; and another conduit connected at one end with said outlet of said heat exchanger and connected at its opposite end to, said inlet opening of said stator, whereby said conduits are cooperable with said stator and heat exchanger to provide an uninterrupted circulating system iorsaid brake liquid normally maintained under superatmospheric pressure.

22.- A device for absorbing the energy of a driven member, comprising: a hydraulic brake unit including a stator adapted to contain brake liquid, and a rotor in said stator adapted to be connected with said driven member, said stator having an inlet opening and an outlet opening connected at its opposite end with said inlet of said heat exchanger; another conduit means connected at one end with said outlet 0! said heat exchanger and connected at its opposite end to said inlet opening of said stator, whereby said conduit means are cooperable with said stator and heat exchanger to provide a closed, uninterrupted circulating system for said brake liquid and means for varying at will the volume of brake liquid in said system to change the load absorption capacity of said brake unit.

23. A device as defined in claim 22, in which the means operable at will for varying the volume of brake liquid in the closed system comprises, a manually operable loading valve and a manually operable unloading valve arranged to admit brake liquid into said system and to drain brake liquid from said system, respectively.

24. A device'as defined in claim 22, in which the means operable at will for varying the volume of brake liquid in the closed system comprises, a loading valve and an unloading valve arranged for admitting brake liquid into said system andfor draining brake liquid from said system, respectively;. and a manually operable remote control device connected'with said valves for controlling the operation thereof.

25. A device as defined in claim 22, in which the means operable at will for varying the volume of brake liquid in the closed system comprises, an electromagnetic loading valve for admitting brake liquid into said system and an electromagnetic unloading valve for draining brake liquid from said system and a remotecontrol device connected with said electromagnetic valves'and including two switches, one for eflecting opening of each of said valves. a

' 26.1A device as defined in claim 22, in which the means operable at will for varying the volume of brake liquid in the closed system comprises, an electromagnetic loading valve for admitting brake liquid, into said system and an electromagnetic, unloading valve for draining brake liquid from said system; and a portable remote control device connected with said electromagnetic valves and adapted to be held in the hand of the operator, said remote control device including two switches, one for effecting opening of each of said valves;

27. A device for absorbing the energy of a drivenn ember, comprising: a hydraulic brake unit including a stator adapted to contain a brakeliquid, and'a rotor in said stator adapted to be connected withsaid driven] member, said stator having an outlet and an inlet; and means includinga heat exchanger for cooling said brake liquid connecting said outlet with; said inlet and providing an uninterrupted fiowjpath of fixed volume for brake liquid exteriorly, of said stator, said fiow path being completely filled with a continuous stream of brake liquid under hydraulic pressure normally above atmospheric pressure when said, brake unit is in operation, said 'rotor serving as an impeller when rotating to continuously force brake liquid out of said stator at a given rate into and through said flow path including'said heat exchanger, and back into said stator at the same rate, whereby the volume of brake liquid in said stator is maintained constant regardless of the speed of said rotor.

28. Adevice for absorbingthe energy of a driven member, comprising: a hydraulic brake unit including a stator adapted to contain a brake liquid, and a rotor in said stator adapted to be connected with said driven member, said stator having an outlet and an inlet; means including a heat exchanger for cooling said brake liquid connecting said outlet with said inlet and providing an uninterrupted flow path of fixed vol-. ume for brake liquid exterior-1y of said stator, said flow path being completely filled with a continuous stream of brake liquid under hydraulic pressure normally above atmospheric pressure when said brake unit .is in operation, said rotor serving as an impeller whenrotating to continuously force brake liquid out of said stator at a given rate into and through said flow path including said heat exchanger, and back into said stator at the same rate, whereby the volume of brake liquid in said stator is maintained constant regardless of the speed of said rotor; and means operable at will to vary the volume of brake liquid available for circulation by said rotor to change the load absorption capacity of said brake unit as desired.

29. In combination, a devicefor absorbing the 24 energy of a rotating'element, comprising: a drum-likestator adapted to contain a liquid, saidstator having a central hub portion, a shaft rotatably mounted in said hub portion and adapted to be connected with said rotating e1e-,

. ment, and a rotor in said stator secured to said shaft; a heat'exchanger for cooling the liquid of saidenergy absorption device, said heat exchanger havingan inlet and an outlet for, said liquid; and a pair of conduits interconnecting'said energy absorption device and said heat exchanger for circulation of said brake liquid through said heat exchanger, by said rotor, one of said conduits connebtingsaid inlet of said heat exchanger with said stator and communicating with the interior of said stator at a point adjacent the periphery thereof and theother of said conduits connecting said 'outletof said heat exchange? with said stator and communicating with the interior of said stator at a point adjacent thehub portion thereof, said conduits and. heat exchanger normallybeing closed to the atmosphere.

30. Ir comblnation, a device for absorbing the energy of a rotating element, comprising; a drum-like casing adapted .to contain a liquid, said casing having a central hub portion, a shaft rotatably mounted in said hub portion and adapted to be connected with said rotating element, and a rotor in said casing secured to said shaft; a heat exchanger for cooling the liquid of said energy absorption device, said heat exchanger liavingan inlet and an outlet for said liquid; 9. pair of conduits interconnecting said energy absorption device and said heat exchanger arranged to form a circulating system normally closed to the atmosphere, one of said conduits connecting said inlet of said heat exchanger with the interior of said casing adjacent the periphery thereof and the other of said conduitsconnecting said outlet of said heat exchanger with the interior of said casing adjacent the hub portion thereof; and means for controlling and varying the volume of liquid in said system, whereby to maintain the capacity of said energy absorption device constant or to vary the same,

, as desired.

31. The method of absorbing the torque of a rotating element, comprising the steps of: introducing a sufiicient volume of brake liquid into a low pressure area of the working circuit of a hydraulic brake to impose a desired load upon said rotating element; eflecting the withdrawal of brake liquid from a relatively high pressure.

area of said working circuit at a given rate; circulating the withdrawn brake liquid through a system normally closed to the atmosphere but in direct communication with said areas; cooling the brake liquid while it is circulating through said system; and returning the cooled brake liquid from said system to said ,working circuit at a rate equal to that at which it is being withdrawn from said working circuit, whereby to maintain a constant volume of brake liquid in said working circuit and a constant load upon said rotating element.

32. The method as defined in claim 31, including the step of circulating the withdrawn brake liquid through the closed system under hydraulic pressure above atmospheric pressure.

33. The method as defined in claim 31, including the step of varying, at will, the total volume of brake liquid to be circulated through said system to vary the load imposed upon the rotating clement.

34. The method of absorbing the torque of a 25 rotating element, comprising the steps of: introducing a suilicient volume of brake liquid into the working circuit of a hydraulic brake to impose-a desired load upon said rotating element; effecting the withdrawal of brake liquid from said working circuit at a given rate; circulating the withdrawn brake liquid through a system having an inlet and an outlet communicating directly with said working circuit and being under hydraulic pressure above atmospheric pressure; cooling the brake liquid while it is circulating through said system; and returning cooled brake liquid to said working circuit at a rate equal to that at which it is .being withdrawn from said working circuit, whereby to maintain a constant volume of brake liquid in said working circuit and a constant load upon said rotating element.

35. The method of absorbing the torque of a rotating element, comprising the steps of: introducing a suflicient volume of brake liquid into the working circuit of a hydraulic brake to impose a desired load upon said rotating element;

effecting the flow of brake liquid from said working circuit at a given rate, directly into the inlet of an uninterrupted flow system normally maintained under superatmospheric pressure while preventing flow of the brake liquid to the atmosphere; circulating the brake liquid through said system; cooling the brake liquid while it is circulating through said system; and returning cooled brake liquid from the outlet of said system to said working circuit at a rate equal to that at which it is being withdrawn therefrom, whereby to maintain a constant volume of brake liquid in said working circuit and a constant load upon said rotating element.

36. The method of absorbing the torque of a rotating element, comprising the steps of: introducing a sufllcient volume of brake liquid into the working circuit of a hydraulic rotor-type brake to impose a desired load upon said rotating element; utilizing the impelling action of the rotor to continuously displace brake liquid from said working circuit at a given rate and to force the same through a zone normally closed to the atmosphere and back into said working circuit at a rate equal to that at which the brake liquid is displaced from said working circuit, whereby to maintain a constant volume of brake liquid in said working ciicuit and a constant load upon said rotating element; and cooling the brake liquld while it is circulating through said zone.

37. The method of absorbing the torque of a rotating element, comprising the steps of: introducing a suilicient volume of brake liquid into the working circuit of a hydraulic rotor-type brake to impose a desired load upon said rotating element; utilizing the impelling action of the rotor to continuously displace brake liquid from said working circuit at a given rate and to force the same through a zone normally maintained under superatmospheric pressure, while preventing flow oi the brake liquid to the atmosphere, and back into said working circuit at a rate equal to that at which the brake liquid is displaced from said working circuit, whereby to maintain a constant volume of brake liquid in said working circuit and a constant load upon said rotating element; and cooling the brake liquid while it is circulating through said zone.

' 38. The method of absorbing the torque of a rotating element, comprising the steps of: introducing a sumcient volume of brake liquid into a low pressure zone of the working circuit of a hydraulic brake to impose a desired load upon said rotatig element; eifectlng the withdrawal of brake liquid from a relatively high pressure zone of said working circuit at a given rate; conducting the withdrawn brake liquid in the form of a continuous stream from said high pressure zone through a predetermined flow path; cooling the brake liquid while it is circulating through said path; and returning cooled brake liquid-to said working circuit at a rate equal to that at which it is being withdrawn therefrom. whereby to maintain a constant volume of brake liquid in said working circuit and a constant load upon said rotating element.

39. A dynamometer, comprising: a hydraulic brake unit for absorbing power developed by an engine being tested, said brake unit including a housing adapted to contain water for use as a brake liquid, a brake shaft rotatably mounted in said housing, and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet and an outlet for said brake liquid; conduit means connecting the respective ends of said heat exchanger with said housing and providing a closed circulating system for the brake liquid normally closed to the atmosphere, said heat exchanger containing a plurality of tubes arranged so that the brake liquid in traversing said heat exchanger must flow through said tubes, said rotor serving to cause forced circulation of the brake liquid from said housing at a given flow rate and into and through said heat exchanger and back into said housing at the same flow rate; supply pipe means for supplying cooling water to said heat exchanger and for supplying water to said brake unit housing; drain pipe means for discharging the cooling water to waste after it has passed through said heat exchanger and for discharging water from said housing to waste; a valve arranged in said supply pipe means to control the admission of water into said brake housing to increase the load absorption capacity of said brake unit; and a valve arranged in said drain pipe means for controlling the discharge of water from said brake housing to decrease the load absorption capacity of said brake unit.

40. A dynamometer, comprising: a hydraulic brake unit for absorbing the power developed by an engine being tested, said brake unit including a housing adapted to contain a brake liquid, a brake shaft rotatably mounted in said housing, and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet and an outlet; conduit means connecting said inlet and outlet with said housing and establishing an uninterrupted flow path between the interior of said housing and said heat exchanger normally under superatmospheric pressure when in use, said rotor serving to cause forced circulation of the brake liquid through said heat exchanger and conduit means in a manner to return brake liquid from said heat exchanger to said housing at the same rate at which said rotor forces brake liquid out of said housing and into said heat exchanger; a supply pipe for supplying brake liquid to said housing to increase the load absorption capacity of said brake unit, said supply pipe having a valve connected therein; and a drain pipe for discharging brake liquid from said housing to decrease the load absorption capactiy of said brake unit, said drain pipe being connected with said supply pipe at a point between said housing and said valve, said. drain pipe having a valve connected therein adjacent its point of connection with said supply pipe.

41. A dynamometer, comprising: a hydraulic brake unit for absorbing the power developed by an engine being tested, said brake unit includin a housing adapted to contain a brake liquid, a brake shaft rotatably mounted in said housing. and a rotor within said housing mounted upon said brake shaft; a heat exchanger having an inlet header, an outlet header, a return flow manifold, a pipe connecting said inlet header with said manifold, another pipe connecting said outlet header with said manifold, and a plurality of tubes in each of said pipes interconnecting said headers and manifold; conduit means connecting said inlet and outlet headers with said housing and establishing an uninterrupted flow path between the interior of said housing and said heat exchanger normally under superatmospheric pressure when in use, said rotor serving to cause forced circulation of the brake liquid through said heat exchanger and conduit means in a manner .to return brake liquid from said heat exchanger to said housing at the same rate at which said rotor forces brake liquid out of said housing and into said heat exchanger; a supply pipe for supplying brake liquid to said housing to increase the load absorption capacity of said brake unit, said supply pipe having a'valve connected therein; and a drain pipe for discharging brake liquid from said housing to decrease the load absorption capacity of said brake unit, said drain pipe being connected with said supply pipe at a point between said housing and said valve, said drain pipe having a valve connected therein adjacent its point of connection with said supply pipe.

EDWIN L CLINE.

. REFERENCES CITED The following references are of record in the file of this patent:

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